Jijun Tang

High-sensitive determination of human α-thrombin by its 29-mer aptamer in affinity probe capillary electrophoresis

ACE technique provides an effective tool for the separation and identification of disease‐related biomarkers in clinical analysis. In recent years, a couple of synthetic DNA or RNA oligonucleotides, known as aptamers, rival the specificity and affinity for targets to antibodies and are employed as one kind of powerful affinity probe in ACE. In this work, based on high affinity between antithrombin aptamer and thrombin (their dissociation constant is 0.5 nM), a carboxyfluorescein‐labeled 29‐nucleotide (nt) aptamer (F29‐mer) was used and an aptamer‐based affinity probe CE (aptamer‐based APCE) method was successfully established for high‐sensitive detection and quantitative analysis of thrombin. Experimental conditions including incubation temperature and time, buffer composition, and concentration of cations were investigated and optimized. Under the optimized condition, the linear range was from 0 to 400 nM and the LOD was 2 nM (74 ng/mL, S/N = 3), i.e., 40 amol, both in running buffer and in 5% v/v human serum. This LOD is the lowest one than those achieved by the previous APCE methods but based on a 15‐mer aptamer. This approach offers a promising method for the rapid, selective, and sensitive detection of thrombin in practical utility. Further binding experiments using one carboxyfluorescein‐labeled aptamer and the other nonlabeled aptamer or vice versa were carried out to deduce the formation of ternary complex when these two aptamers coexisted in the free solution with thrombin.

A photoluminescent nanocrystal-based signaling protocol highly sensitive to nerve agents and highly toxic organophosphate pesticides

A photoluminescent II-VI group semiconductor nanocrystal (NC)-based signaling platform composed of thioglycolic acid capped CdS NCs and acetylcholinesterase-acetylthiocholine enzyme catalytic reaction system was developed that was shown to be highly sensitive to nerve agents and toxic organophosphate pesticides with detection limits down to sub-nM levels. This new sensing protocol does not require troublesome conjugation of biomacromolecules onto the surface of NCs.